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Strain budget of the Ecuador–Colombia subduction zone: A stochastic view

Gombert, B. and Duputel, Z. and Jolivet, R. and Simons, M. and Jiang, J. and Liang, C. and Fielding, E. J. and Rivera, L. (2018) Strain budget of the Ecuador–Colombia subduction zone: A stochastic view. Earth and Planetary Science Letters, 498 . pp. 288-299. ISSN 0012-821X. https://resolver.caltech.edu/CaltechAUTHORS:20180720-093538407

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Abstract

The 2016 Pedernales earthquake (M_W=7.8) ruptured a portion of the Colombia–Ecuador subduction interface where several large historical earthquakes have been documented since the great 1906 earthquake (M=8.6). Considering all significant ruptures that occurred in the region, it has been suggested that the cumulative moment generated co-seismically along this part of the subduction over the last century exceeds the moment deficit accumulated inter-seismically since 1906. Such an excess challenges simple models with earthquakes resetting the elastic strain accumulated inter-seismically in locked asperities. These inferences are however associated with large uncertainties that are generally unknown. The impact of spatial smoothing constraints on co-seismic and inter-seismic models also prevents any robust assessment of the strain budget. We propose a Bayesian kinematic slip model of the 2016 Pedernales earthquake using the most comprehensive dataset to date including InSAR and GPS offsets, tsunami waveforms, and kinematic records from high-rate GPS and strong-motions. In addition, we use inter-seismic geodetic velocities to produce a probabilistic inter-seismic coupling model of the subduction interface. Our stochastic co-seismic and inter-seismic solutions include the ensemble of all plausible models consistent with our prior information and that fit the observations within uncertainties. The analysis of these model ensembles indicates that an excess of co-seismic moment during the 1906–2016 period is likely in Central Ecuador only if we assume that 1942 and 2016 earthquakes are colocated. If this assumption is relaxed, we show that this conclusion no longer holds given uncertainties in co- and inter-seismic processes. The comparison of 1942 and 2016 teleseismic records reveals large uncertainties in the location of the 1942 event, hampering our ability to draw strong conclusions on the unbalanced moment budget in the region. Our results also show a heterogeneous coupling of the subduction interface that coincides with two slip asperities in our co-seismic model for the 2016 Pedernales earthquake and with the location of historical ruptures in 1958, 1979 and 1998. The spatial variability in coupling and complexity in earthquake history suggest strong heterogeneities in frictional properties of the subduction megathrust.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.epsl.2018.06.046DOIArticle
ORCID:
AuthorORCID
Jolivet, R.0000-0002-9896-3651
Simons, M.0000-0003-1412-6395
Jiang, J.0000-0002-8796-5846
Fielding, E. J.0000-0002-6648-8067
Rivera, L.0000-0002-0726-5445
Additional Information:© 2018 Elsevier. Received 6 April 2018, Revised 15 June 2018, Accepted 29 June 2018, Available online 20 July 2018. Editor: J.-P. Avouac The ALOS-2 original data are copyright JAXA and provided under JAXA RA4 PI Project P1372002. The Copernicus Sentinel-1 data were provided by the European Space Agency (ESA). Contains modified Copernicus data 2016, processed by ESA and NASA/JPL. We thank the Instituto Geofísico de la Escuela Politécnica Nacional (IG-EPN Ecuador) and the IRD for making available the static GPS, high-rate GPS and accelerometers data used in this study. Aside from the data from the IG-EPN and IRD networks, the data set also includes accelerometer data from OCP and GPS data from the Instituto Geográfico Militar (IGM) and Servicio Geológico Colombiano, Proyecto GeoRED from Colombia, that we also thank. The waveform of the 1942 earthquake used on this study was provided by Lingling Ye and Hiroo Kanamori. This project has received funding from the Agence Nationale de la Recherche (ANR-17-ERC3-0010), the European Union's Horizon 2020 research and innovation program (grant agreement 758210), and the CNRS international program for scientific co-operation (PICS). This research was also supported by the NASA Earth Surface and Interior focus area and performed at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. We thank the Editor, Jean-Philippe Avouac, and two anonymous reviewers for their constructive comments, which helped improve this manuscript.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Japan Aerospace Exploration Agency (JAXA)P1372002
Agence Nationale pour la Recherche (ANR)ANR-17-ERC3-0010
European Research Council (ERC)758210
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
NASA/JPL/CaltechUNSPECIFIED
Subject Keywords:Ecuador–Colombia subduction zone; strain budget; bayesian inversion; kinematic source model; geodetic coupling model
Record Number:CaltechAUTHORS:20180720-093538407
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180720-093538407
Official Citation:B. Gombert, Z. Duputel, R. Jolivet, M. Simons, J. Jiang, C. Liang, E.J. Fielding, L. Rivera, Strain budget of the Ecuador–Colombia subduction zone: A stochastic view, Earth and Planetary Science Letters, Volume 498, 2018, Pages 288-299, ISSN 0012-821X, https://doi.org/10.1016/j.epsl.2018.06.046. (http://www.sciencedirect.com/science/article/pii/S0012821X18303972)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:88049
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:23 Jul 2018 14:32
Last Modified:09 Mar 2020 13:19

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